Hydrothermal treatment of renewable raw material

ABSTRACT

The present invention relates to a particulate carbon material that can be produced from renewable raw materials, in particular from biomass containing lignin, comprising: a 14C content that corresponds to that of the renewable raw materials, said content being preferably greater than 0.20 Bq/g carbon, especially preferably greater than 0.23 Bq/g carbon, but preferably less than 0.45 Bq/g carbon in each case; a carbon content in relation to the ash-free dry substance of between 60 ma. % and 80 ma. %; an STSA surface area of the primary particles of at least 5 m2/g and at most 200 m2/g; and an oil absorption value (OAN) of between 50 ml/100 g and 150 ml/100 g. The present invention also relates to a method for producing said carbon material and to the use thereof.

The present invention relates to methods for producing particulatecarbon material

DESCRIPTION

There is a wide range of applications for particulate carbon material.One application is the use as filler for polymers such as elastomers;thermoplastics and thermosets. In the production of rubber articles fromelastomers fillers are used in order to influence therubber-technological properties of the cross-linked rubber articles,e.g. measured as tensile strength, hardness, rigidity or tear strength.Furthermore, the product properties such as for example the rollingresistance, abrasion and wet grip performance of vehicle tires therebyare adjusted. Influencing the rubber-technological properties by afiller also is referred to as reinforcement.

The fillers most widely used at present include carbon black and silica.Carbon black mostly is produced by the pyrolysis of natural gas,petroleum parts and/or coal-based oils, wherein in dependence on thecarbon black quality considerable amounts of carbon dioxide aregenerated during the production. Precipitated silica is produced fromwater glass, wherein during the production of water glass large amountsof carbon dioxide also are obtained.

With the shortage of fossil carbon resources (cf, petroleum- andcoal-based oils as carbon black raw material), the saving of chemicals(see sulfuric acid in the precipitation of silica), but above all withthe avoidance of carbon dioxide emissions from fossil sources (seedecomposition of carbonate in the production of water glass; seecombustion of oil or gas in the precombustion chamber of carbon blackreactors as well as the partial combustion of the carbon black rawmaterial in the formation of carbon black) there is an increasing demandfor the production of industrial products on the basis of renewable rawmaterials. In renewable raw materials all the carbon originates fromatmospheric carbon dioxide. With an energetic utilization of renewableraw materials the carbon dioxide balance hence is largely neutral. Witha material utilization of renewable raw materials no fossil carbon isreleased during the production, and even atmospheric carbon is bound inthe carbonaceous material—at least for the period of use of therespective products.

In the following, there is described a particulate carbon material onthe basis of renewable raw materials to be used as a filler, which hassurprisingly good properties in use as a filler in elastomers ascompared to the classically produced fillers carbon black and silica.

In the following, the meaning of terms used here is described:

A filler is a particulate solid that is added to an elastomer,thermoplastic or thermoset. Depending on the property of the filler,e.g. when added to elastomers, the rubber-technological properties of across-linked rubber mixture (e.g. cross-linked by vulcanization) areinfluenced to varying degrees by adding the filler, in general togetherwith further additives, before cross-linking.

Silica is a typical filler. Silica in essence means precipitated silica,which chiefly is used in rubber articles, In addition, there also ispyrogenic silica.

Carbon black is another typical filler. This always means industrialcarbon black, i.e, a specifically technically produced carbon black withdefined properties. Carbon black chiefly is produced by incompletecombustion or pyrolysis. Here, carbon black does not mean anyby-products of a combustion like in the case of diesel soot or chimneysoot.

The reinforcing effect of carbon black and/or silica greatly correlateswith the primary particle size of the filler. The primary particle sizeis directly related to the specific surface area.

Against this background, carbon blacks with small surface area arereferred to as inactive carbon blacks, carbon blacks with medium surfacearea are referred to as semi-active carbon blacks, and carbon blackswith large surface area are referred to as active carbon blacks, whereinactivity here means the degree of the reinforcing effect of therespective carbon blacks in the rubber. See also ASTM D 1765. Typically,inactive carbon blacks have BET surface areas <30 m²/g, semi-activecarbon blacks 30-70 m²/g, and active carbon blacks 90 to >150 m²/g. Theimportance of the surface area as a guidance parameter also becomesclear from the fact that the first digit of the ASTM carbon blacksreflects the particle size and the surface area, respectively. In thecase of silica, this differentiation is less pronounced. Silica with adistinct reinforcing effect typically has a BET surface area >100 m²/g.In the following, filler means a product that achieves at least theperformance of an inactive carbon black. A performance that is at leastcomparable to that of an inactive carbon black subsequently also isreferred to as reinforcing effect. A typical inactive carbon black isN990.

The particle surface is composed of the outer and the inner surface. Theassociated measurement quantity is the specific surface area of theparticulate material. The specific surface area can be measured as theouter surface area by means of statistical thickness surface area, forshort STSA, or as total surface area comprising outer and inner surfacearea by means of nitrogen surface area according to Brunauer, Emmett andTeller, for short BET. The difference between inner and outer surfacearea substantially results from the porosity of the material. Beside thesurface surrounding the particles, the inner surface area also relatesto the surface present in pores. A coarsely divided material, which hasa comparatively small outer (i.e. STSA) surface area, nevertheless canhave a large total (i.e. BET) surface area (comprising outer and innersurface area), when it is highly porous.

To describe the fineness of a material with reference to values of thespecific surface area, only the STSA surface area strictly speaking isto be employed. Conversely, the difference “BET surface area minus STSAsurface area” is a measure for the porosity of finely divided materials,as it represents the surface area of the pores. The smaller thedifference is, the less porous the material. In the case of non-porousmaterials, BET also very well describes the fineness.

The determination of the BET surface area and the STSA surface area iseffected corresponding to the standard ASTM D 6556-14. In the presentinvention, in contrast to this standard, the samplepreparation/outgassing for the STSA and BET measurements is effected at150° C.

The methods and their significance likewise are described in“Kautschuktechnologie” (Fritz Röthemeier, Franz Sommer, 3rd edition,Carl Hanser Verlag München 2013) on page 289 with reference to theexample of a classical carbon black. The most important method fordetermining the specific surface area is the measurement of the nitrogenadsorption according to Brunauer, Emmett and Teller (BET method). Asample of the carbon black is first heated in a vacuum in order toremove the substances adsorbed on the surface. After cooling, the sampleis exposed to nitrogen at boiling temperature (77 K), and the adsorbedvolume as well as the associated equilibrium vapor pressure aredetermined. At low pressures, a monomolecular layer first is formed, towhich further layers are attached with increasing pressure. The specificsurface area can be determined by evaluating the adsorption isothermaccording to the BET method with a nitrogen partial pressure of 0.1 to0.3. For routine determinations single-point measurements aresufficient.

The determination of the surface area by means of N2 adsorption providesa larger surface area for microporous carbon blacks, as the nitrogenmolecules can also penetrate the pores. This effect can be avoided byusing surface-active substances that are larger than the pores (CTABmethod) or by determining the N2 adsorption at higher partial pressures(0.2 to 0.5) and a further evaluation (STSA method).

STSA method (Statistical Thickness Surface Area): The evaluation makesuse of the same measurement data as in the BET method, but themeasurement is made at higher partial pressures (0.2 to 0.5). The STSAmethod is based on the so-called t-plot evaluation method according tode Boer, later on modified by Magee. It is assumed here that theadsorption is locally different in various stack heights, which thenhave a statistical thickness. The STSA surface area likewise isindicated in m²/g and is a measure for the “outer” surface area of acarbon black particle, but above all it is a measure for therubber-active surface area.

When comparing the performance of carbon black or silica in cross-linkedrubber articles it is expedient in view of the known dependence betweenspecific surface area and performance to compare fillers with a similarspecific surface area. Similar surface area here and in the followingmeans that the BET values of non-porous materials or the STSA values areapart by not more than approximately 10-20 m²/g.

Carbon black and silica are built up of primary particles. Thesegeometric units, which do not exist in isolated form, but are visible inpictorial representations, are intergrown to form aggregates, whereinthe intergrowth is effected by strong chemical bonds. Aggregates inaddition can be clustered to form agglomerates, wherein the connectionof several aggregates to agglomerates is effected by weak forces.Agglomerates can be destroyed by dispersion. The degree of the aggregateformation is described in obsolete form by DBP absorption or morerecently by oil absorption. For more details see ASTM D 2414. Referencealso is made to the oil absorption number with the abbreviation OAN. Ahigh value of the DBP or oil absorption designates a material withstrongly branched aggregates. In carbon black above all the so-calledstructure has a direct influence on its reinforcing effect.

The performance of carbon black or silica in rubber applicationsgenerally is determined by measuring rubber-technological characteristicquantities. Rubber-technological characteristic quantities describecertain properties of a rubber mixture in the cross-linked, for examplevulcanized condition. In so far, rubber articles in this document areunderstood to be the finished articles made of rubber after theircross-linkage and vulcanization, respectively. In the present document,these finished rubber articles also are referred to as rubber parts,molded articles, articles made of elastomer material or rubber product.From the wide variety of rubber parts in various fields of application amultitude of different quantities is obtained to describe rubber parts.Depending on the field of application, values of a quantity referred toas positive can also be assessed as negative elsewhere. What isprimarily used as rubber-technological characteristic quantities is thetensile strength (ASTM D 412, DIN 53504), tear strength (DIN 53455) aswell as the stress values at a strain of 50%, 100%, 200% and 300% (DIN53504), hereinafter referred to as so-called modulus 50%, modulus 100%,modulus 200% and modulus 300%, respectively. Furthermore, the hardness(ASTM D 2240) for example can play a role. For these quantities,however, values that are high, but not too high, are regarded aspositive.

As a further rubber-technological characteristic value, the loss factortan delta is used as a quotient from the loss modulus E″ and the storagemodulus E′ of the elastomer material. A distinction is made between thevalue of tan delta in a high temperature range, in particular the tandelta at 60° C., and the tan delta in the lower temperature range, inparticular the tan delta at 0° C. While the tan delta at 60° C. suggeststhe rolling friction of a tire, the tan delta at 0° C. is used to assessthe wet grip of a tire. For the tan delta at 60° C. low values arepreferred in this connection, and for the tan delta at 0° C. high valuesare preferred. The tan delta values are determined in connection with adynamic mechanical analysis (temperature sweep). In the case describedhere, the dynamic mechanical analysis (DMA) is carried out withprism-shaped molded pieces of the dimensions 2×10×35 mm for thetemperature variation on an Eplexor 150N Dynamic Mechanical ThermalSpectrometer.

Untreated silica is a filler with polar functional groups, which insulfur-crosslinked systems can disturb the cross-linkage. Thedisturbance of the sulfur cross-linkage for example can be based on theadsorption of vulcanization aids on the polar functional groups of thefiller surface. In addition, for example, the different surface energiesof polymer and filler can prevent a good dispersion of the filler in thepolymer and when reheating of the mixture (e.g. during thevulcanization) can lead to an undesired re-agglomeration of the fillerparticles dispersed already (so-called filler flocculation). This is thestarting point for the addition of reagents to the silica. In thesimplest case the polar groups of silica are reacted with suitable basiccompounds, whereby these groups are deactivated or masked. The silica assuch in this way as a whole is activated in its function as reinforcingfiller, i.e. the surface chemistry of silica is adapted to the surfacechemistry of the polymer due to this activation or masking. See also:Fritz Röthemeier, Franz Sommer, 3rd edition, Carl Hanser Verlag München2013 on pages 301-302.

To improve the rubber-technological properties, silica generally is usedwith coupling reagents. Coupling reagents are bifunctional compoundsthat bind to silica on the one hand and to rubber on the other hand andthus can produce a connection between the silica and the rubber. This isparticularly important, as silica and rubber per se are chemicallyincompatible with each other. A typical coupling reagent isbis(triethoxypropylsilyl)tetrasulfide in use of silica in rubber.

In the plastics application adhesion promoters are used, which likewiseprovide a connection between the polymer and a further component, whichcan be another polymer or a filler. In the present document couplingreagent also is understood to be an adhesion promoter.

In the field of powder characterization the grain size or the grain sizedistribution often is indicated as well. The same chiefly is determinedby laser diffraction or sieve analysis. In general, it is eitherindicated what percentage the number (Q0 distribution) or the volume (Q3distribution) of particles of a particular geometric expansion has inthe total amount of particles. The indication usually is made in μm. Thegrain size refers to the size of the particle present in separate formunder the concrete conditions. It depends on the dispersion medium andthe dispersion quality. The grain size does not distinguish betweenparticles as a result of macroscopic caking for example by foreignsubstances, particles as a result of microscopic agglomeration due toinsufficient dispersion effort, or particles in the form of isolatedaggregates or primary particles. It indicates the expansion of a bodydelimited to the outside, even if the same possibly consists of severalconnected parts. By means of the material density (raw density) the massdistribution can be calculated from the volume distribution.

The morphology of fillers can be fibrous, platelet-shaped or spherical.As a distinction criterion the length-to-diameter ratio can be used. Theexpansions in various directions in space for this purpose aredetermined for example by means of electron microscopic measurements(TEM, REM). Often, reference also is made to the aspect ratio, thequotient of largest and smallest expansion. It can be indicated both inthe form x:y and in the form of the calculated quotient. As calculatedquotient, a sphere hence would have an aspect ratio of 1, ellipsoidstructures of approximately 1.5 to 2, and fiber-like structures morethan 10.

Conventional carbon black, which is produced from raw materials offossil origin, i.e, on the basis of coal tar, natural gas or petroleum,in the following is referred to as classical carbon black. In contrastthereto reference is made to biogenic carbon black when the carbon blackhas been produced from renewable raw materials.

Raw materials of fossil origin above all are all substances derived frompetroleum, such as distillates, distillation residues or petroleumcomponents treated by cracking processes. The fossil raw materialslikewise include all products obtained during the distillation, cokingor liquefaction of lignite, hard coal or anthracite. Natural gas also isa fossil raw material. All fossil carbon sources have in common thattheir ¹⁴C content lies below that of renewable raw materials, as they nolonger participate In the steady exchange of isotopes.

Renewable raw materials on the other hand are all products derived fromthe direct utilization of plants or animals. When thinking of the carbonblack production process, this can be primarily vegetable oils or animalfats. In a broader sense and hence in the sense of this document, thisincludes any biomass.

Biomass includes all organic substances accessible from the utilizationof plants or animals or obtained as wastes of this utilization;including secondary products and wastes produced or separated therefrom.Without being able to make a restriction here, typical forms of biomassinclude wood, straw, sugar, starch, vegetable oil, leaves, shells,bagasse, empty fruit bunches, fermentation residues, green cuttings ororganic municipal waste. It is usual to designate organic material thathas a shorter regeneration time than peat as biomass. Especially, thisalso includes wastes from the industrial use of plants. For example, inthe pulp industry large amounts of wood are processed, in whichlignin-containing wastes such as black liquor are obtained. Allbiomasses have in common that their ¹⁴C content lies above that offossil raw materials, as they participate in the steady exchange ofisotopes.

One type of biomass is lignin, which is obtained in some wood processingprocesses. Lignin is a naturally occurring polymer that primarily can bederived from the fundamental building blocks cumaryl, coniferyl andsinapyl alcohol. Depending on the process of wood processing, it isobtained as large amounts of KRAFT lignin, generally dissolved in blackliquor, hydrolysis lignin or lignin sulfonate. Depending on the pH valuein the respective processing process, the hydrogen atoms in the hydroxylgroups typical for lignin can proportionately be replaced by metalcations. Strictly speaking, the lignin sulfonate already is a chemicalderivative of lignin, as it has additional sulfonate groups insertedduring processing.

HTC is an abbreviation for hydrothermal carbonization. This is thetreatment of a substance in aqueous phase under pressure-sealedconditions and at elevated temperature. Due to the elevated pressure itis possible to carry out reactions in liquid water, in which thetemperature is far above 100° C., i.e. above the boiling point of waterat normal pressure.

According to the prior art, fillers with a reinforcing effect chieflyare used to improve the rubber-technological properties of rubberarticles. The two fillers most widely used for rubber applications arecarbon black and silica. Carbon black almost exclusively is obtainedfrom fossil raw materials. As the product according to the invention isa particulate carbon material usable e.g. as filler, which is obtainedfrom renewable raw materials, the classical carbon blacks obtained fromfossil raw materials do not belong to the prior art. Silica is a fillerthat is obtained from inorganic silicon compounds. Therefore, silicaslikewise do not belong to the prior art.

A subject of research activities is the development of alternativefillers from renewable raw materials. The key aim pursued by the vastmajority of these development efforts is to reproduce the properties ofcarbon black in the best possible way by refining renewable rawmaterials. This relates in particular to the carbon content, which isgenerally adjusted to more than 90%, but also to the fraction ofgraphitic carbon. The materials thus produced therefore are alsoreferred to as bio-based carbon black. The parallel aim mostly is toprovide a filler from renewable raw materials, which at least partly cansubstitute the classical carbon blacks. Furthermore, there aredevelopment efforts that aim at directly using the renewable rawmaterials as a filler, possibly after a purification, fractionation orcomminution.

From WO 2010/043562 A1 it is known for example that carbon black alsocan be produced from renewable raw materials. As a filler withespecially narrower aggregate size distribution the disclosed carbonblack is said to above all have an improved modulus in rubberapplications. In terms of their fundamental properties the carbon blackscharacterized in WO 2010/043562 A1 lie within the range of the classicalcarbon blacks N220 and N375. The carbon black described here is producedby the classical furnace process, wherein natural gas is used in aprecombustion chamber and fossil carbon is released. The carbon blackobtained has a sulfur content of max. 2.5%, a content of volatilecomponents according to DIN 53552 of max. 2.5%, and hence roughly acarbon content of more than 95% carbon.

WO 2014/096544 A1 claims a carbon product that is formed of porouscarbon particles with a surface area of more than 500 m²/g and anaverage pore volume of less than 1 ml/g, which in turn consist ofprimary particles, such as aggregates, that have a particle size of lessthan 250 nm. The carbon product is obtained from the hydrothermalcarbonization of biomaterial that has more than 40% carbon based on thedry weight. Starting substances include lignin, tannin and betulin,hydrolysis lignin, products from the manufacture of paper, plates,biofuel or brewing products. The carbon content of the productsdescribed in the examples lies between 77.31 and 86.44% carbon. Thestrong carbonization of the material indicated in the examples meansthat other elements such as above all oxygen and hydrogen must bedepleted. This necessarily leads to the disadvantage that the surfacechemistry of the material depletes, i.e. there are less functionalgroups on the surface. The reduced number of surface groups has adisadvantageous effect on possible binding mechanisms to the polymer.

It is also known to directly use renewable raw materials such as ligninor lignin derivatives both without and with coupling reagents in rubbermixtures in order to influence the rubber-technological properties inthe cross-linked condition.

For example, DE 10 2008 050 966 A1 describes a rubber mixture thatcontains a lignin derivative, more especially a lignin sulfonic acidderivative, up to alkali or alkaline earth salts of lignin sulfonicacid. The rubber mixture produced by using this lignin sulfonic acidderivative in addition can also contain carbon black or siliceous earth.The application also claims a tire made of the aforementioned rubbermixture. As is shown by the examples disclosed in DE 10 2008 050 966 A1,it is disadvantageous that the lignin derivatives always are used beside40 phr carbon black or 80 phr siliceous earth/5 phr carbon black. Theterm siliceous earth in this document is used for silica. Hence, thereis only achieved an improvement of the rubber-technologicalcharacteristic quantities in combination with the classical fillers.

When using renewable raw materials in rubber mixtures with the aid ofcoupling reagents, reference is made in particular to the expertise inthe use of silica.

Of silica it is known in principle that in sulfur-crosslinked systemsfillers with polar functional groups, such as e.g. untreated silica,disturb the cross-linkage. At the same time it is known that thisdisturbance can be mitigated by adding suitable reagents such as aminesor glycols. The functional groups are blocked or masked. See also: FritzRöthemeier, Franz Sommer, 3rd edition, Carl Hanser Verlag München 2013on pages 301-302.

As regards the reinforcement with silica it is known that the effect ofsilica can be improved considerably by coupling reagents. There are usedfunctional alkoxy silanes that on the one hand can bind to silica onmixing with the alkoxy silane group by forming an Si—O—Si bond and lateron bind to the rubber polymer with a further function during thevulcanization, possibly with the participation of added sulfur. Suitablereinforcing bright fillers include silica and silicates. By treating thesilica with silanes, the mechanical properties and the processingproperties are substantially improved (see Fritz Röthemeier, FranzSommer:

Kautschuktechnologie, 3rd edition, Carl Hanser Verlag München 2013,pages 112-113, chapter 2.5.4.3 Fillers).

Similarly, uses of silane as coupling reagent in renewable rawmaterials, which will be used as fillers, are known.

EP 2 223 928 A1 describes a functionalized lignin, wherein groupscontained in the lignin react with functionalizing agents and thesereagents can be anhydrides, esters and silanes. Furthermore, there isdisclosed a rubber mixture that contains functionalized lignin asfiller, possibly mixed with classical carbon black or silica, andoptionally a coupling reagent for the functionalized lignin or for thesilica.

It is also known to produce finely divided materials (which would beusable as fillers) by hydrothermal carbonization (HTC).

By way of example reference is made to WO 2014/122163 A1, whichdescribes a method for producing a carbon-enriched biomass material, theobtained biomass material and its use. The feedstock lignocellulosematerial is treated at elevated temperature, preferably at maximally120-130° C., and partially oxidizing conditions, i.e. in thesub-stoichiometric presence of oxygen, preferably in a range of0.15-0.45 mol/kg of dry lignocellulose material, and after opening thereactor solid products optionally are separated from the reactionmixture. The feedstock has a moisture content between 10% and 70% and asize between 0.2 and 100 mm. The applied pressure lies between 1 and 100bar, absolute. As reaction time, 2-500 min are indicated. There ispreferably used 0.1-1 kg of water or steam/kg of lignocellulose. Thecarbon concentration is increased by 8-25%. The obtained materialcontains a maximum of 45-60% carbon, beside 5-8% hydrogen and 35-50%oxygen. As use, merely the combustion is indicated, especially in theground condition for dust firing.

Furthermore, there is known a method for obtaining carbonized ligninwith a defined grain size distribution from a liquid containing lignin,wherein the liquid containing lignin is subjected to a hydrothermalcarbonization, whereby the lignin is transferred into a carbonizedlignin, and the carbonized lignin is separated from the liquidcontaining the carbonized lignin, the liquid containing lignin issubjected to a hydrothermal carbonization at temperatures in the rangefrom about 150° C. to about 280° C., and the grain size distribution ofthe carbonized lignin is adjusted by adapting the H⁺ ion concentrationin the liquid containing lignin before and/or during the hydrothermalcarbonization. Thus, it is known that by adjusting the H⁺ ionconcentration of a liquid containing lignin, the distribution of thegrain size of the obtained product, i.e, the size of the agglomerates,can be influenced.

It is the object of the invention to provide a particulate carbonmaterial from renewable raw materials usable for example as a filler,which for example when used in rubber mixtures after their cross-linkageat rubber technological characteristic quantities shows a comparableperformance as a classical carbon black similar in terms of the BET/STSAsurface area. In addition, it is the object of the invention to providean efficient method with respect to the use of energy and adjuvants, bymeans of which the material according to the invention can be produced.

The object is solved by a particulate carbon material with the featuresof claim 1 and by a method for producing the same with the features ofclaim 9.

Correspondingly, there is provided a particulate carbon materialproducible from renewable raw materials, in particular fromlignin-containing biomass, with the following features:

-   -   a ¹⁴C content corresponding to that of renewable raw materials,        preferably greater than 0.20 Bq/g of carbon, in particular        preferably greater than 0.23 Bq/g of carbon, preferably however        each less than 0.45 Bq/g of carbon;    -   a carbon content based on the ash-free dry substance between 60        wt-% and 80 wt-%;    -   an STSA surface area of at least 5 m²/g and maximally 200 m²/g;        and    -   an oil absorption number (OAN) between 50 ml/100 g and 150        ml/100 g.

As mentioned above, lignin-containing biomass and here in particularlignin-containing biomass with a content of Klason lignin of more than80% preferably is used as renewable raw material (to determine thelignin content the Klason method is employed, in which thepolysaccharides are decomposed by a two-stage acid hydrolysis and theremaining lignin residue subsequently is weighed as Klason lignin).Lignin is obtained as a by-product of fractionation processes of woodybiomass. During the fractionation processes, the lignin typically eitheris dissolved and then separated from the non-soluble components of thewoody biomass (e.g. KRAFT process) or the woody biomass is depolymerizedsuch that the lignin chiefly remains as a solid (e.g. hydrolysisprocess). Depending on the type of fractionation process, the ligninaccordingly either is present dissolved in a liquid containing lignin,for example black liquor, or as a liquid generally dewateredmechanically. When the lignin is present dissolved in a liquidcontaining the lignin, the lignin can be precipitated from the same ingeneral for example by using acids or acidicaliy acting gases and beobtained as a mechanically dewatered solid (see for example theLignoBoost process).

The ¹⁴C content, which corresponds to that of renewable raw materials,distinguishes the present particulate carbon material, which can be usede.g. as a filler in elastomers, thermoplastics or thermosets, fromclassical carbon black that is obtained on the basis of fossil rawmaterials. In the present case, the particulate carbon material has a¹⁴C content greater than 020 Bq/g of carbon, in particular preferablygreater than 0.23 Bq/g of carbon, preferably however each less than 0.45Bq/g of carbon.

The ¹⁴C content in biomass grown in the year 1950, i.e, at the beginningof the extensive nuclear weapon tests of mankind, was about 0.226 Bq/gof carbon. During the time of the nuclear weapon tests it grew up to0.42 Bq/g of carbon and presently again approximately returns to theoriginal level. In 2009, 0.238 Bq/g of carbon were measured. To delimitthe carbon material according to the invention against materials withartificially enriched ¹⁴C content, the ¹⁴C content in the carbonmaterial according to the invention hence is at most 0.45 Bq/g ofcarbon.

The carbon content based on the ash-free dry substance of more than 60wt-% and less than 80 wt-%, preferably of more than 65 wt-% and lessthan 75 wt-%, more preferably of more than 68 wt-% and less than 74wt-%, in addition preferably of more than 70 wt-% and less than 73 wt-%(carbon content by elemental analysis according to DIN 51732; ashcontent according to DIN 51719 at 815° C.) distinguishes the presentparticulate carbon material usable as filler from renewable rawmaterials directly used as filler such as wood flour, etc., whichtypically have a lower carbon content. Furthermore, the carbon contentbased on the ash-free dry substance of more than 60 wt-% and less than80 wt-% distinguishes the present particulate carbon material fromproducts produced from renewable raw materials for example byfractionation, extraction, distillation or crystallization, such assugar, starch, cellulose, etc., which typically have a lower carboncontent based on the ash-free dry substance of 40 wt-% to 50 wt-%.Furthermore, the present particulate carbon material in its preferredembodiment differs from lignin that has been separated from biomass bymeans of a KRAFT process, which typically has a carbon content based onthe ash-free dry substance of 65 wt-%.

The carbon content based on the ash-free dry substance of more than 60wt-% and less than 80 wt-% also distinguishes the present particulatecarbon material from classical carbon black that has been produced bythe usual carbon black production processes or the variants of thebio-based carbon black, which are produced both by the usual carbonblack production methods and also for example by pyrolysis, partialoxidation, carbonization or similar methods, which typically have ahigher carbon content based on the ash-free dry substance of about 95%and more. Also in the case of highly oxidized carbon blacks with acontent of volatile components at 950° C. according to DIN 53552 of 20%and in addition 2.5% sulfur, the carbon content based on the ash-freedry substance roughly is more than 88%.

An advantage of the low carbon content of the present product ascompared to carbon black consists in that the surface functionalityoriginating from the renewable raw materials partly is maintained andcan be utilized in the application for example via coupling reagents.

The STSA surface area of at least 5 m²/g and maximally 200 m²/g,preferably between 8 m²/g and 100 m²/g, furthermore distinguishes thepresent particulate carbon material from non-porous lignin or non-porousparticulate material that has been produced by the hydrothermalcarbonization, which usually has BET surface areas of less than 2 m²/g,wherein the—generally not measured—STSA surface areas naturally will beslightly below this value.

Furthermore, the present particulate carbon material thereby differsfrom particulate materials made of renewable raw materials, which have ahigh specific BET surface area due to their high porosity, such as forexample pyrolysis coals, coals obtained via partial oxidation, coalsobtained via hydrothermal carbonization, and activated carbons, due tothe fact that the present particulate carbon material largely is notporous and very finely divided, which is seized by the STSA surfacearea.

In one variant of the present particulate carbon material, the STSAsurface area has values between 10 m²/g and 80 m²/g, preferably between12 m²/g and 70 m²/g, more preferably between 15 m²/g and 70 m²/g, inparticular preferably between 20 m²/g and 70 m²/g.

Advantageously, the BET surface area of the present particulate carbonmaterial only differs from the STSA surface area by maximally 20%,preferably by maximally 15%, more preferably by maximally 10%.Advantageously, the pore volume of the particulate carbon material is<0.1 cm³/g, more preferably <0.01 cm³/g, particularly preferably <0.005cm³/g. Hence, the present particulate carbon material differs fromfinely divided porous materials such as for example ground biogenicpowdered activated carbon, which beside a BET surface area of generallymore than 500 m²/g can also have an STSA surface area of maximally 10m²/g.

What is an advantage of the large STSA surface area as compared tolignin and HTC coals is the particular fineness of the product, whichprovides for a high degree of interactions between the present productand e.g. polymers. It is an advantage of the almost non-existentporosity of the present product that for example as compared to theutilization of porous carbon materials additives and cross-linkingchemicals cannot lose their effectiveness by penetrating the pores.

Advantageously, the average size of the primary particles of theparticulate carbon material however is limited to a value of greaterthan 8 nm, preferably greater than 10 nm, more preferably greater than15 nm.

Advantageously, primary particles of the particulate carbon materialhave a heterogeneous size distribution. The smaller particle fractionaccordingly has a size of greater than 8 nm, preferably greater than 10nm, more preferably greater than 15 nm up to a size of 250 nm. Thelarger particle fraction has sizes above 250 nm.

Advantageously, the primary particles are intergrown to form aggregates,whereby the size of the primary particles differs from the size of theaggregates. Preferably, the size of the primary particles then is below250 nm. In this preferred case, the primary particles are smaller thanaggregates, preferably on average by at least a factor of 2, morepreferably on average by at least a factor of 4. For clarification itshould be added that in this preferred embodiment, too, primaryparticles can be present individually and can then theoretically beequated with aggregates. In this preferred embodiment, however, thisonly rarely is the case, preferably for less than 25%, more preferablyfor less than 20%, particularly preferably for less than 15%. Thisapplies in particular for primary particles with a size of more than 250nm.

As the size of the primary particles and aggregates is not or onlyinsufficiently available by measuring the grain size, for example bylaser diffraction or sieve analysis, images taken with a scanningelectron microscope for example can be utilized to determine thesesizes.

The oil absorption number (OAN) between 50 ml/100 g and 150 ml/100 gdistinguishes the present particulate carbon material from carbonmaterials pulverized for example by grinding or steam explosion, whichhave smaller OAN values due to the missing aggregates or aggregatesdestroyed by the grinding process.

In another variant of the present particulate carbon material, the OANvalue lies between 65 m¹/100 g and 150 ml/100 g, more preferably between70 ml/100 g and 130 ml/100 g, moreover preferably between 75 ml/100 gand 130 ml/100 g, in particular preferably between 80 ml/100 g and 120m¹/100 g. The OAN absorption is determined according to the standardASTM D 2414-00.

An advantage of the high oil absorption number as compared to carbonproducts with a lower oil absorption number is the presence ofaggregates that have an advantageous effect on the interactions betweenthe present particular carbon material and for example polymers.

In one variant, the present particulate carbon material has a watercontent of less than 5 wt-%, preferably less than 3 wt-%, morepreferably less than 2 wt-%. The present low water content or the drycondition of the carbon material provides for incorporating the sameinto polymers, e.g. as a filler, because a generation of steam bubblesat high temperature is avoided. In addition, increased moisture of thecarbon material is disturbing for the use of coupling reagents.

In another embodiment, a 15% suspension of the particulate carbonmaterial in distilled water has an electrical conductivity of less than5 mS/cm, preferably less than 3 mS/cm, and particularly preferably lessthan 2 mS/cm. The electrical conductivity (determined as conductance ofthe measuring probe of the device PCE-PHD1 at 20° C. to 25° C.) in thepresent case serves as a measure for the ion content or the ionconcentration, in particular of ions selected from the group includingNa⁺, Ca²⁺, SO₄ ²⁻, CO₃ ²⁻, S²⁻, HS⁻. An advantage of the lowconductivity is the small content of water-soluble ions, which mightseparate from the present product even when used for example inpolymers.

Moreover, an embodiment of the particulate carbon material in a 15%suspension in distilled water has a pH value of >6, preferably >7, morepreferably >8. Preferably, the pH value of a 15% suspension of theparticulate carbon material in distilled water is less than 10, morepreferably less than 9. An advantage of the neutral or slightly basic pHvalue of the present product for example is its good compatibility withthe other components of the polymer mixture.

It also is advantageous when the present particulate carbon material hasa DIG signal ratio in the Raman spectrum between 0.20 and 0.90,preferably between 0.40 and 0.75, more preferably between 0.45 and 0.70,as a measure for the content of graphitic carbon.

As a measure for the content of graphitic carbon in the material thearea ratio DIG of the D-band to the G-band in the Raman spectrum can beused. The D-band (disorder band) lies above 1300 cm⁻¹ up toapproximately 1360 cm⁻¹, and the G-band (graphite band) lies atapproximately 1580-1590 cm⁻¹. To calculate the area ratio DIG, theintegrals of the Raman spectrum over the D-band and the G-band arecalculated and then brought into relation.

An advantage of the indicated DIG ratio consists in that the material insome applications—due to its content of graphitic carbon—can be utilizedlike a classical carbon black, and in addition—due to its content ofamorphous carbon and the elements bound thereto—further functionalitiesare available.

In another embodiment, the present particulate carbon material has a lowsolubility in a basic solution.

Advantageously, the present particulate carbon material accordingly hasa high resistance to bases. In the present case, a high resistance tobases means that less than 40%, preferably less than 30%, particularlypreferably less than 15%, in particular less than 10% of the presentparticulate carbon material are dissolved. Preferably, the procedure todetermine the resistance to bases is as follows;

-   -   weighing in solid, dry particulate carbon material that        previously has been washed twice with five times the weight each        of distilled water;    -   suspending in distilled water, so that the content of dry        substance is about 5%;    -   increasing the pH value of the distilled water to a value of        about 9 by adding sodium hydroxide solution;    -   increasing the temperature of the pH-adjusted suspension of the        present carbon material and distilled water to about 80′C;    -   stirring for a time of 2 hours under the above conditions;    -   after cooling the suspension to room temperature, repeating the        process from the step of adjusting the pH value, until the pH        value again corresponds to about 9 after cooling the suspension        to room temperature;    -   centrifugation of the suspension for 15 minutes at 9000        revolutions per minute;    -   separation of the liquid phase and drying of the remaining solid        residue; and    -   weighing the dried residue.

The resistance to bases in percent is determined by dividing the dryweight of the weighed residue by the dry weight of the particulatecarbon material weighed in and by multiplying this by 100. Thesolubility of the particulate carbon material in percent is determinedby subtracting the resistance to bases from 100.

In so far, the particulate carbon material according to the inventiondiffers from lignin in that its resistance to bases is distinctlyincreased. This has the advantage that e.g. in the case of the use asfiller in rubber products or plastic products the present particulatecarbon material is not easy to wash out from the rubber product orplastic product upon contact with water.

Advantageously, the particulate carbon material according to theinvention has a surface chemistry comparable to silica. A surfacechemistry comparable to silica means that the present carbon materialhas a high OH-group density. In particular, the oxygen content of thepresent ash-free particulate carbon material lies between 20 wt-% and 30wt-%, preferably between 20 wt-% and 25 wt-%.

In so far, the present particulate carbon material differs from carbonblack that is obtained from renewable raw materials for example by anintensive carbonization (pyrolysis, oxidation, hydrothermalcarbonization, etc) in that the functional groups of the renewable rawmaterials used for producing the present particulate carbon materialwere not largely separated by the thermal treatment, but still areavailable for binding to polymers or coupling reagents.

Preferably, the ash content of the particulate carbon material based onthe dry substance is at least 1 wt-%, but less than 8 wt-%, morepreferably at least 2 wt-% and less than 6 wt-%, moreover preferably atleast 3 wt-% and less than 6 wt-%, in particular at least 4 wt-% andless than 6 wt-% (ash content according to DIN 51719 at 815° C.).

In a further-reaching variant of the present particulate carbon materialthe D90 of the Q3 distribution of the grain size (as a measure for thesize of the particles present in separated form under the concreteconditions) is less than 30 μm, preferably less than 20 μm, morepreferably less than 15 μm, more preferably less than 10 μm, inparticular less than 5 μm. In a further-reaching variant of the presentparticulate carbon material the D99 of the Q3 distribution of the grainsize is less than 30 μm, preferably less than 20 μm, more preferablyless than 15 μm, more preferably less than 10 μm, in particular lessthan 5 μm. In a further-reaching variant of the present particulatecarbon material the D99 of the Q3 distribution of the grain size is morethan 1 μm, preferably more than 2 μm.

An advantage of the above maximum values of the Q3 distribution of thegrain size consists in that due to the maximum size of the particlespresent in separated form the present particulate carbon material in usefor example in polymers causes no impurity that would lead for exampleto a premature rupture or breakage of the polymer or to surface defectsduring extrusion.

The average sphere diameter determined with the aid of the STSA surfacearea on the assumption of a material density (raw density) of 1500 kg/m³advantageously is at least two times, preferably at least three times,more preferably at least four times, in particular at least six times assmall as the average diameter (D50) measured over the Q3 distribution ofthe grain size of the particle present in separated form. The averagesphere diameter is calculated with the aid of the following formulae:

STSA surface area=sphere surface/(sphere volume*material density)  1.

sphere surface=PI*average sphere diameter{circumflex over ( )}2  2.

sphere volume=1/6*PI*average sphere diameter{circumflex over ( )}3  3.

By inserting 2. and 3. into 1, the following relationship is obtained:

average sphere diameter=6/(STSA surface area*material density)

The measurement of the grain size distribution of the particulate carbonmaterial is made in a 10% suspension with distilled water by means oflaser diffraction. Before and/or during the measurement of the grainsize distribution, the sample to be measured is dispersed withultrasound, until a grain size distribution stable over severalmeasurements is obtained.

The STSA surface area of the present particulate carbon materialpreferably is largely independent of its Q3 distribution of the grainsize and characterizes the fineness of the primary particles.

In a preferred embodiment, the present particulate carbon material has

-   -   a ¹⁴C content corresponding to that of renewable raw materials,        preferably greater than 0.20 Bq/g of carbon, in particular        preferably greater than 0.23 Bq/g of carbon, preferably however        each less than 0.45 Bq/g of carbon;    -   a carbon content based on the ash-free dry substance between 60        wt-% and 80 wt-%;    -   an STSA surface area of at least 5 m²/g and maximally 200 m²/g;    -   an oil absorption number (OAN) between 50 ml/100 g and 150        ml/100 g; and    -   a D90 of the Q3 distribution of the grain size of less than 20        μm, preferably of less than 15 μm.

Advantageously, the present particulate carbon material has a shape thatlargely corresponds to the shape of classical carbon black. A shape ofthe present particulate carbon material comparable to classical carbonblack for example is given by the fact that the particulate carbonmaterial

-   -   consists of few porous primary particles,    -   several of which are intergrown to form aggregates, and    -   the same in turn are at least partly agglomerated.

In so far, the present particulate carbon material usable e.g. as afiller differs from fillers according to the prior art, which forexample are obtained by grinding renewable raw materials, in that thefiller has a distinct structure that is comparable to the structure ofclassical carbon blacks. The shape can be determined for example byusing SEM images.

The particulate carbon material usable as a filler preferably has anon-fibrous morphology, which means that the aspect ratio is less than10, preferably less than 5.

In another preferred embodiment, the present particulate carbon materialhas

-   -   a ¹⁴C content corresponding to that of renewable raw materials,        preferably greater than 0.20 Bq/g of carbon, in particular        preferably greater than 0.23 Bq/g of carbon, preferably however        each less than 0.45 Bq/g of carbon;    -   a carbon content based on the ash-free dry substance of more        than 60 wt-% and less than 80 wt-%;    -   an STSA of at least 5 m²/g and maximally 200 m²/g;    -   an OAN of 50 ml/100 g to 150 ml/100 g;    -   a surface chemistry comparable to silica; and    -   a shape that largely corresponds to the shape of classical        carbon black.

By the advantageous combination of the properties of a classical carbonblack with respect to its shape with that of silica with respect to itssurface chemistry, this preferred embodiment of the present particulatecarbon material has a similar potential for interactions between fillerand polymer as a classical carbon black and provides for additionallycompleting this interaction potential e.g. by coupling reagents via asimilar mechanism such as silica.

The particulate carbon material can be used for example as filler orreinforcing filler. The particulate carbon material according to theinvention can be used for example in rubber or rubber mixtures orplastics.

Another subject-matter of the invention is polymer mixtures that arecharacterized by the fact that they contain at least one polymer and atleast one particulate carbon material according to the invention.Polymers can be thermoplastics, thermosets or elastomers.

A list of polymers is indicated for example in WO 2010/043562 A2 frompage 10, line 20 to page 12, line 36, into which the particulate carbonmaterial according to the invention can be incorporated. Preferredpolymers are selected from a list with the following plastics orrubbers: polyester, polyethylene, polypropylene, polyester carbonates,polyamides, polyimides, polyester amides, polyether imides,polyurethanes, polyvinyl alcohols, polyvinyl acetates, polyvinylchlorides, polymethacrylates, polystyrenes, styrene maleic anhydride,polycaprolactone, polybutylene terephthalate, polyepoxides; celluloseproducts such as cellulose acetate or cellulose nitrate, vulcanizedfiber, polylactic acid, polyhydroxy alkanoates, chitin, casein, gelatin;formaldehyde resins, such as melamine-formaldehyde resin,urea-formaldehyde resin, melamine-phenol resins, phenol-formaldehyderesins; silicone polymer, natural rubber, styrene-butadiene copolymers,polybutadiene, polyisoprene, isobutylene-isoprene copolymers,ethylene-propylene-diene copolymers, acrylonitrile-butadiene copolymers,chloroprene, fluorine rubber or acrylic rubber and mixtures thereof.

Another subject-matter of the invention is rubber mixtures that arecharacterized by the fact that they contain at least one rubber and atleast one particulate carbon material according to the invention.

The particulate carbon material can be used in quantities of 10 wt-% to150 wt-%, preferably 20 wt-% to 120 wt-%, more preferably 40 wt-% to 100wt-%, particularly preferably 50 wt-% to 80 wt-%, based on the weight ofthe used rubber.

The rubber mixture preferably contains at least the particulate carbonmaterial according to the invention and in addition naturally occurringmineral, siliceous, calcareous or lime-containing fillers.

Preferably, the rubber mixture contains the particulate carbon materialaccording to the invention and a coupling reagent, preferably anorganosilane. The organosilanes can be for examplebis(trialkoxysilylalkyl)oligosulfide or -polysulfide, for examplebis(triethoxysilylpropyl)disulfide orbis(triethoxysilylpropyl)tetrasulfide, mercaptosilanes, aminosilanes,silanes with unsaturated hydrocarbon groups, for example vinyl silanes.Ultimately, silanes with large saturated hydrocarbon groups, for exampledodecyltriethoxysilane, also can act like coupling reagents, whereinhowever no covalent bonds, but rather van-der-Waals forces effect acertain coupling to the polymer.

The organosilane preferably is used in quantities of 2 wt-% to 16 wt-%,more preferably 4 wt-% to 14 wt-%, particularly preferably 6 wt-% to 12wt-%, based on the weight of the used particulate carbon material.

When using an organosilane together with an expression of theparticulate carbon material according to the invention with an STSAsurface area comparable to that of a non-active carbon black, selectedrubber-technological characteristic values preferably are achieved inthe cross-linked condition of the rubber mixture, which are comparableto those achieved when using a semi-active carbon black or a silicatogether with an organosilane.

When using an organosilane together with the particulate carbon materialaccording to the invention, selected rubber-technological characteristicvalues preferably not only are achieved, but also surpassed in thecross-linked condition of the rubber mixture, which are achieved whenusing a carbon black with an STSA surface area comparable to that of theparticulate carbon material.

In another preferred variant the rubber mixture contains the particulatecarbon material according to the invention and a reagent masking thefunctional groups, preferably an organosilane, an amine or a glycol. Inthis connection, for example triethanolamine, hexamethylenetetramine,di-o-tolylguanidine or diphenylguanidine can be used as amine. Suitableglycols include ethylene glycol, tetraethylene glycol or polyethyleneglycol. The organosilane can be a trialkoxysilylalkylsilane, for exampletriethoxymethylsilane, triethoxyethylsilane or triethoxypropylsilane.The above reagents are not able to be incorporated into thecross-linkage via sulfur bridges. However, they react with the surfaceof the carbon material according to the invention by consuming thefunctional groups, so that the same have a less adverse effect on thesulfur cross-linkage. Thus, the triethoxyalkylsilanes do not act like acoupling reagent. Apart from the avoidance of a disturbed sulfurcross-linkage such silanes however act as compatibilizers that adapt thesurface energy of the filler particles to that of the polymer matrix andin this way lead to a distinctly improved dispersibility.

Preferably, a carbon black in a rubber mixture can be substituted by thepresent particulate carbon material for up to 100%, and in thecross-linked condition a performance comparable to carbon black in termsof selected rubber-technological characteristic values nevertheless canbe achieved.

Preferably, silica in a rubber mixture furthermore can be substituted bythe present particulate carbon material for up to 100%, and in thecross-linked condition a performance comparable to silica in terms ofselected rubber-technological characteristic values nevertheless can beachieved, wherein preferably an organosilane is used.

Preferred rubber-technological characteristic values include the modulus50% and the modulus 200% determined in the tensile test. What ispreferred are high values for the modulus 50% and the modulus 200%.

A further preferred rubber-technological characteristic value is theloss factor tan delta (quotient of loss modulus E″ and storage modulusE′ of the elastomer material) at temperatures between 40° C., preferably50° C., more preferably 60° C. and 100° C., determined in a dynamicmechanical analysis (temperature sweep). This characteristic value is awidely used predictor value for the rolling friction in the tireindustry. What is preferred are low values for tan delta in theindicated temperature range, more preferably the tan delta decrease isat least 10% with respect to the carbon black reference, quiteparticularly preferably the tan delta decrease is at least 15% withrespect to the carbon black reference. An additional preferredrubber-technological characteristic value is the loss factor tan deltaat 0° C., determined in a dynamic mechanical analysis (temperaturesweep). This characteristic value is a widely used predictor value forthe wet grip in the tire industry, wherein for tan delta at 0° C. highvalues are preferred, more preferably the tan delta increase is at least10% with respect to the carbon black reference.

In a preferred embodiment, the rubber mixture also contains carbonblacks, preferably semi-active carbon blacks or active carbon blacks,beside the particulate carbon material.

This rubber mixture preferably contains at least the particulate carbonmaterial, at least one carbon black, preferably a semi-active carbonblack or an active carbon black and naturally occurring mineral,siliceous, calcareous or lime-containing fillers.

This rubber mixture preferably contains at least the particulate carbonmaterial, at least one carbon black, preferably a semi-active carbonblack or an active carbon black and naturally occurring mineral,siliceous, calcareous or lime-containing fillers and at least oneorganosilane.

The advantage of the simultaneous use of the particulate carbon materialtogether with a carbon black consists in that particularrubber-technological characteristic values of the vulcanized rubbermixture can be improved.

In another embodiment, the rubber mixture also contains silicas,preferably precipitated and pyrogenic silicas beside the particulatecarbon material according to the invention, and further can containnaturally occurring mineral, siliceous, calcareous or lime-containingfillers and an organosilane.

For producing the rubber mixtures according to the invention, syntheticrubbers also are suitable beside natural rubber (NR). Preferredsynthetic rubbers are described for example in W. Hofmann,Kautschuktechnologie, Genter Verlag, Stuttgart 1980 or in WO 2010/043562from page 15, line 4 to page 15, line 24. Further preferred syntheticrubbers are indicated for example in the following list:Styrene-butadiene copolymers (SBR), polybutadiene (BR), polyisoprene,isobutylene-isoprene copolymers, ethylene-propylene-diene copolymers,acrylonitrile-butadiene copolymers (NBR), chloroprene, fluorine rubberor acrylic rubber and mixtures thereof.

The rubber mixtures according to the invention can contain furtherrubber adjuvants, such as reaction promoters, aging inhibitors, heatstabilizers, light stabilizers, antiozonants, processing aids,plasticizers, tackifiers, blowing agents, dyes, pigments, waxes,diluents, organic acids, retarders, metal oxides as well as activatorssuch as diphenylguanidine, triethanolamine, polyethylene glycol,alkoxy-terminated polyethylene glycol or hexane triol, which are knownin the rubber industry.

Useful cross-linkers include sulfur, organic sulfur donors or radicalformers. The rubber mixtures according to the invention in addition cancontain vulcanization accelerators.

Mixing the rubbers with the particulate carbon material, possibly carbonblacks, possibly silicas, possibly rubber adjuvants and possiblyorganosilanes, can be carried out in usual mixing units such as rollingmills, internal mixers and mixing extruders. Usually, such rubbermixtures are produced in an internal mixer, wherein initially therubbers, the particulate carbon material, possibly carbon blacks,possibly silica, possibly rubber adjuvants and possibly organosilanesare admixed in one or more successive thermomechanical mixing stages ata temperature of 100° C. to 170° C. The sequence of addition and thetime of addition of the individual components can have a decisive effecton the properties of the mixture obtained. The rubber mixture thusobtained then is usually mixed with the cross-linking chemicals in aninternal mixer or on a rolling mill at 40-120° C. and processed toobtain the so-called green compound for the succeeding process steps,such as for example shaping and vulcanization.

The vulcanization of the rubber mixtures according to the invention canbe effected at temperatures of 80° C. to 200° C., preferably 130° C. to180° C., possibly under a pressure of 10 to 200 bar.

The rubber mixtures according to the invention are suitable formanufacturing rubber articles, i.e. articles made of the completelycross-linked or vulcanized elastomers, so-called molded articles, forexample for manufacturing pneumatic tires, tire treads, tire side walls,cable sheaths, hoses, drive belts, conveyor belts, roll coverings,tires, shoe soles, buffers, sealing rings, profiles and dampingelements.

Another subject-matter of the invention is plastic mixtures that arecharacterized by the fact that they contain at least one plastic and atleast one particulate carbon according to the invention. Plastic in thisconnection means a thermoplastic or thermoset.

The particulate carbon material can be used in quantities of 10 wt-% to150 wt-%, preferably 20 wt-% to 120 wt-%, more preferably 30 wt-% to 100wt-%, based on the weight of the used plastic.

Preferably, the plastic mixture contains the particulate carbon materialaccording to the invention and an adhesion promoter or a couplingreagent.

Preferably, promoting the adhesion is based on the use of maleicanhydride or other organic acids, preferably unsaturated carboxylicacids. Useful adhesion promoters also include for example silanes,preferably with particularly large hydrocarbon residues, for exampledodecyltriethoxysilane.

The adhesion promoter preferably is used in quantities of 2 wt-% to 16wt-%, more preferably 4 wt-% to 14 wt-%, particularly preferably 6 wt-%to 12 wt-%, based on the weight of the plastic used.

Plastics include for example polyethylene (PE), polypropylene (PP),polyvinyl acetate (PVA) or thermoplastic elastomers (TEP). The plasticmixtures according to the invention preferably are used formanufacturing cables, tubes, fibers, films, in particular agriculturalfilms, engineering plastics and injection molded articles.

The present particulate carbon material is produced by a methodaccording to the invention, which in particular provides for adjustingthe STSA surface area and the OAN value to the range indicated above.

According to the invention, there is provided a multi-stage, inparticular four-stage method for the hydrothermal treatment, inparticular carbonization of renewable raw materials, in particular ofrenewable raw materials with a content of more than 80% Klason lignin,in which

-   -   in a first step a liquid containing the renewable raw material        is provided,    -   which in a second step is subjected to a hydrothermal treatment        at a temperature between 150° C. and 250° C.,    -   in a third step the solid present after the hydrothermal        treatment is largely separated from the liquid, and    -   the residual moisture of the solid in a fourth step largely is        removed by drying, whereby a particulate carbon material is        obtained, wherein the STSA surface and the OAN value of the        particulate carbon material obtained in the fourth step are        controlled by mutually matching    -   the concentration of the organic dry matter of the renewable raw        material in the liquid containing the renewable raw material,    -   the pH value of the liquid containing the renewable raw        material,    -   the concentration of inorganic ions in the liquid containing the        renewable raw material,    -   the temperature of the hydrothermal treatment, and    -   the residence time in the hydrothermal treatment, and thus an        STSA surface area of at least 5 m²/g and maximally 200 m²/g and        an OAN value of at least 50 ml/100 g and maximally 150 ml/100 g        is adjusted.

Preferably, instead of the concentration of the inorganic ions of theliquid containing the renewable raw material the conductance of theliquid containing the renewable raw material is employed.

By mutually matching the pH value, the conductivity and the amount ofinorganic dry matter as well as the temperature and the residence timein the hydrothermal treatment, conditions are applicable during thehydrothermal treatment that lead to obtaining the present particulatecarbon material. In particular, the pH value and the conductivity arechanged during the hydrothermal treatment and only in the course of theprocess form conditions that produce the present particulate carbonmaterial.

Preferably, the STSA surface area and the OAN value of the particulatecarbon material obtained in the fourth step are controlled by mutuallymatching

-   -   the concentration of the organic dry matter of the renewable raw        material in the liquid containing the renewable raw material,    -   the pH value of the liquid containing the renewable raw        material,    -   the concentration of inorganic ions in the liquid containing the        renewable raw material,    -   the temperature of the hydrothermal treatment, and    -   the residence time in the hydrothermal treatment,        and the desired STSA surface area is adjusted in that with a        desired increase of the STSA surface area    -   the concentration of the organic dry matter of the renewable raw        material in the liquid containing the renewable raw material is        decreased and/or    -   the pH value of the liquid containing the renewable raw material        is increased and/or    -   the concentration of inorganic ions in the liquid containing the        renewable raw material is decreased.

Furthermore preferably, the desired STSA surface area is adjusted inthat with a desired increase of the STSA surface area the temperature ofthe hydrothermal treatment is increased and/or the residence time in thehydrothermal treatment is prolonged.

Preferably, with a desired increase of the STSA surface area thetemperature of the hydrothermal treatment is increased and/or theresidence time in the hydrothermal treatment is prolonged when the yieldof dry particulate carbon material is very low, preferably less than10%, furthermore preferably less than 20%, moreover preferably less than30%, particularly preferably less than 40%, each based on the dry weightof the renewable raw material.

Preferably, the STSA surface area and the OAN value of the particulatecarbon material obtained in the fourth step are controlled by mutuallymatching

-   -   the concentration of the organic dry matter of the renewable raw        material in the liquid containing the renewable raw material,    -   the pH value of the liquid containing the renewable raw        material,    -   the concentration of inorganic ions in the liquid containing the        renewable raw material,    -   the temperature of the hydrothermal treatment, and    -   the residence time in the hydrothermal treatment,        and the desired STSA surface area is adjusted in that with a        desired reduction of the STSA surface area    -   the concentration of the organic dry matter of the renewable raw        material in the liquid containing the renewable raw material is        increased and/or    -   the pH value of the liquid containing the renewable raw material        is decreased and/or    -   the concentration of inorganic ions in the liquid containing the        renewable raw material is increased.

More preferably, the desired STSA surface area preferably is adjusted inthat with a desired reduction of the STSA surface area the temperatureof the hydrothermal treatment is lowered and/or the residence time inthe hydrothermal treatment is shortened.

What is meant by temperature and residence time not only is the maximumtemperature that is maintained over a certain residence time, but thetemperature-time profile that is passed through in the second step. Whenno temperature-time profile is indicated below, temperature howevermeans the maximum temperature that is maintained over a certainresidence time. In the following, temperature and residence time jointlyare referred to as process conditions.

The present method offers the advantage over the prior art that theformation of the desired finely divided particles is not terminatedalready in the first step, but conditions that lead to the formation ofthe particulate carbon material with a corresponding STSA surface areaand OAN value only are accomplished during the hydrothermal treatment inthe second step.

Only such a procedure provides for at the same time accomplishing aparticle formation and a reaction which in the end leads to aparticulate carbon material that differs from the used renewable rawmaterial also with regard to its carbon content or its resistance tobases.

The present method in particular has the advantage that by the preferredadjustment and mutual matching

-   -   of the concentration of the organic dry matter of the renewable        raw material in the liquid containing the renewable raw        material,    -   of the pH value of the liquid containing the renewable raw        material,    -   of the concentration of inorganic ions in the liquid containing        the renewable raw material,    -   of the temperature of the hydrothermal treatment, and    -   of the residence time in the hydrothermal treatment,        the polymerization of the renewable raw material in the second        step largely is suppressed or limited to such an extent that a        particulate carbon material with a corresponding STSA surface        area and CLAN value is obtained, and via the grain size        distribution, i.e. the size distribution of the agglomerates or        the particles present in separated form under certain        conditions, the size of the primary particles can be influenced        directly, which is seized by the STSA surface area. In addition,        the build-up of porosity in the material is suppressed, which is        revealed by a small difference between STSA surface area and BET        surface area of the particulate carbon material.

Preferably, for the adjustment and mutual matching

-   -   of the concentration of the organic dry matter of the renewable        raw material in the liquid containing the renewable raw        material,    -   of the pH value of the liquid containing the renewable raw        material,    -   of the concentration of inorganic ions in the liquid containing        the renewable raw material,    -   of the temperature of the hydrothermal treatment, and    -   of the residence time in the hydrothermal treatment,        one or more of the following measured quantities is employed:    -   specific density of the liquid containing the renewable raw        material after the second step;    -   conductivity of the liquid containing the renewable raw material        after the second step;    -   pH value of the liquid containing the renewable raw material        after the second step;    -   difference of the pH value of the liquid containing the        renewable raw material before and after the second step;    -   difference of the conductances of the liquid containing the        renewable raw material before and after the second step;

Advantageously, the STSA surface area and the OAN value of theparticulate carbon material obtained in the fourth step are controlledby adjusting

-   -   the concentration of the organic dry matter of the renewable raw        material in the liquid containing the renewable raw material        preferably to a value between 5 wt-% and 40 wt-%, more        preferably between 10 wt-% and 20 wt-%,    -   the pH value of the liquid containing the renewable raw material        at 20° C. to 25° C. preferably to a value ≥7, more preferably        ≥8, in particular preferably ≥8.5, more preferably ≥11,    -   the concentration of inorganic ions in the liquid containing the        renewable raw material preferably to a value between 10 mS/cm        and 200 mS/cm, preferably between 10 mS/cm and 150 mS/cm, more        preferably between 10 mS/cm and 50 mS/cm, moreover preferably        between 10 mS/cm and 40 mS/cm, in particular preferably between        10 mS/cm and 25 mS/cm (determined as conductance of the        measuring probe of the PCE-PHD1 at 20° C. to 25° C.),    -   the temperature of the hydrothermal treatment preferably to a        maximum value between 200° C. and 250° C., preferably to a        maximum value between 210° C. and 245° C. and/or    -   the residence time in the hydrothermal treatment preferably to a        period between 1 minute and 6 hours, preferably between 30        minutes and 4 hours, in particular preferably between 1 hour and        3 hours,        and thus an STSA surface area between 5 m²/g and 200 m²/g and an        OAN value between 50 ml/100 g and 150 ml/100 g is adjusted.

Advantageously, the renewable raw material in the first step iscompletely dissolved in the liquid containing the renewable rawmaterial. Alternatively, the renewable raw material in the first step isnot completely dissolved in the liquid containing the renewable rawmaterial, wherein however

-   -   the concentration of the organic dry matter of the renewable raw        material in the liquid containing the renewable raw material,    -   the pH value of the liquid containing the renewable raw        material,    -   the concentration of inorganic ions in the liquid containing the        renewable raw material        are adjusted such that due to the temperature increase during        the hydrothermal treatment in the second step the renewable raw        material initially is dissolved completely, before the solid        separable in the third step is formed in the second step.

An advantage of the complete dissolution of the renewable raw materialin the liquid containing the renewable raw material consists in that asolid-solid transition is suppressed and the solid separable in thethird step is formed completely from the solution, i.e. a transitionfrom the solution to the solid occurs.

Advantageously, the method is operated continuously, wherein the processconditions of the hydrothermal treatment are kept constant in the secondstep and a continuous adjustment of the pH value and the conductance ofthe liquid containing the renewable raw material is effected in thefirst step in order to compensate fluctuations in the quality of therenewable raw material.

This procedure has the advantage that the substantially more expensiveadjustment of the process conditions in the second step can be avoided.

In a particular variant of the method, the temperature and the residencetime are adjusted in the second step such that to achieve an STSAsurface area between 5 m²/g and 200 m²/g and an OAN value between 50ml/100 g and 150 ml/100 g

-   -   a slightly higher concentration of inorganic ions is required        than is initially obtained after the adjustment of the organic        dry matter content of the renewable raw material in the liquid        containing the same and the adjustment of the pH value, and    -   subsequently, a further increase of the concentration of        inorganic ions by addition of salts can be made, until the        concentration of inorganic ions, as measured by the conductance,        appropriate for the process conditions of the second stage has        been achieved.

This procedure has the advantage that the conductance can be used forthe fine adjustment of the quality of the liquid containing therenewable raw material, as the same can be measured much more easily andreliably than the pH value.

Advantageously, the adjustment of the concentration of the organic drymatter of the renewable raw material in the liquid containing therenewable raw material, of the pH value of the liquid containing therenewable raw material, and/or of the concentration of inorganic ions inthe liquid containing the renewable raw material is effected in thefirst step.

Alternatively, the adjustment of the concentration of the organic drymatter of the renewable raw material in the liquid containing therenewable raw material, of the pH value of the liquid containing therenewable raw material, and/or of the concentration of inorganic ions inthe liquid containing the renewable raw material advantageously iseffected in the first step and in the second step.

Alternatively, the adjustment of the concentration of the organic drymatter of the renewable raw material in the liquid containing therenewable raw material, of the pH value of the liquid containing therenewable raw material, and/or of the concentration of inorganic ions inthe liquid containing the renewable raw material advantageously iseffected in the second step.

In the embodiments in which the adjustment of the concentration of theorganic dry matter of the renewable raw material in the liquidcontaining the renewable raw material, of the pH value of the liquidcontaining the renewable raw material and/or of the concentration ofinorganic ions in the liquid containing the renewable raw material alsois effected in the second step, the renewable raw material in the liquidcontaining the renewable raw material advantageously is completelydissolved in the first step and the formation of the desired finelydivided particles during the hydrothermal treatment in the second stepis accomplished not only by the chosen process conditions, but inaddition by increasing the concentration of the organic dry matter ofthe renewable raw material in the liquid containing the renewable rawmaterial, by lowering the pH value of the liquid containing therenewable raw material or by increasing the concentration of inorganicions in the liquid containing the renewable raw material.

It is an advantage of such procedure that the conditions that lead tothe formation of the desired finely divided particles specifically canbe accomplished in the second step and the stability of the methodthereby can be increased and the residence time in the second steppossibly can be reduced.

Moreover, after completion of the formation of the desired finelydivided particles in the second step, a decrease of the concentration ofthe organic dry matter in the liquid containing the particulate carbonmaterial, an increase of the pH value of the liquid containing theparticulate carbon material or a decrease of the concentration ofinorganic ions in the liquid containing the particulate carbon materialadvantageously is accomplished. Advantageously, this already is effectedin the second step or in the third step at the latest.

By this procedure it is ensured that after completion of the formationof the desired finely divided material no further solids are formed forexample during the cooling phase at the end of the second step or due toan increase of the concentration of the organic dry matter in the liquidcontaining the particulate carbon material for example by evaporation inthe third step.

During the hydrothermal treatment the pressure at least corresponds tothe saturated vapor pressure of the liquid containing the renewable rawmaterial.

In a preferred embodiment

-   -   the concentration of organic dry matter of a liquid containing        lignin in the first step lies between 10 wt-% and 20 wt-%, the        pH value of the liquid containing lignin in the first step is        more than 8.5 and less than 10.5,    -   the concentration of the inorganic ions of the liquid containing        lignin in the first step is such that the conductivity lies        between 10 mS/cm and 25 mS/cm,    -   the maximum temperature of the hydrothermal treatment in the        second step lies between 210° C. and 240° C., and the residence        time of the liquid containing lignin in the hydrothermal        treatment in the second step lies between 120 and 240 minutes,        whereby    -   the STSA surface area of the particulate carbon material thus        produced, which is measured after dewatering in the third step        and drying in the fourth step, has a value between 5 m²/g and 50        m²/g and an CAN value between 50 ml/100 g and 100 ml/100 g.

The method according to the invention furthermore can include a washingstep subsequent to dewatering in the third step or a pulverizing stepsubsequent to drying in the fourth step.

Drying in the fourth step preferably is carried out at temperaturesbelow the softening point of the particulate carbon material, preferablyat temperatures below 150° C., more preferably at temperatures below130° C.

Advantageously, the D90 of the Q3 distribution of the grain size of theparticulate carbon material after drying in the fourth step is adjustedby a pulverizing step to a value of less than 30 μm, preferably lessthan 20 μm, more preferably less than 15 μm, and particularly preferablyless than 10 μm.

The method in particular can do without the addition of aco-polymerizable compound or a polymerization initiator and without afermentation of the biomass.

The method operates in the liquid phase, wherein the method always takesplace below the critical point of water.

The present invention will subsequently be explained in detail withreference to exemplary embodiments. In the drawing:

FIG. 1 shows a diagram of the stress-strain distribution in the tensiletest as an example for the rubber-technological characteristic values ofcross-linked rubber articles made of SBR with the particulate carbonmaterial according to the invention and of the associated reference.

FIG. 2 shows a diagram of the curves of the loss factor tan delta(logarithmic scaling) in dependence on the temperature at completelycross-linked articles made of SBR with the particulate carbon materialaccording to the invention and at the reference with N 660,respectively.

FIG. 3 shows a diagram of the stress-strain distribution in the tensiletest as a comparison of the rubber-technological characteristic valuesof cross-linked rubber articles made of SBR, which are provided withuntreated lignin, with the particulate carbon material according to theinvention, but without a coupling reagent, and with the particulatecarbon material according to the invention and a coupling reagent.

FIG. 4 shows a diagram of the stress-strain distribution in the tensiletest as a comparison of the rubber-technological characteristic valuesof cross-linked rubber articles made of SBR, which are provided withparticulate carbon material according to the invention, but without anyfurther additive, with the particulate carbon material according to theinvention and a reagent for masking the functional groups, and with theparticulate carbon material according to the invention and a couplingreagent.

FIG. 5 shows a diagram of the stress-strain distribution in the tensiletest as a comparison of the rubber-technological characteristic valuesmade of elastomer material mixtures based on natural rubber andbutadiene rubber NR/BR and the particulate carbon material, each withdifferent mixing procedures, and of the reference,

FIG. 6 shows a diagram of the stress-strain distribution in the tensiletest as a comparison of the rubber-technological characteristic valuesof cross-linked rubber articles made of SBR, which are provided with theparticulate carbon material according to the invention without acoupling reagent, and of the reference.

The exemplary embodiments describe the method according to the inventionfor obtaining the particulate carbon material according to theinvention, its properties and its performance in the cross-linkedrubber.

Examples 1-11 for Producing the Particulate Carbon Material from Lignin

In a first step a liquid containing the renewable raw material isprovided.

Initially, water (1) and lignin (2) are mixed and a lignin-containingliquid with an adjusted content of organic dry matter (3) is prepared.

The lignin subsequently is completely dissolved in the lignin-containingliquid. For this purpose, the pH value is adjusted to the desired value(7) by adding a base or an acid (6). The preparation of the solution issupported by intensive mixing at a suitable temperature (4) for asufficient period (5). By the added base or acid and by salts that areadded in addition (8) and/or also originate from the ash content of thelignin a particular concentration of inorganic ions is adjusted, whichcan be measured as conductivity (9). The composition and properties ofthe lignin-containing liquid thus prepared are indicated in Table 1

TABLE 1 Example 1 2 3 4 5 6 7 8 9 — ml Type Type g % ° C. h Additive g —Additive g mS/cm 1 10200 distilled water Lignin 1 1800 14.1 80 2 NaOH107.25 10.1 — 0.0 15.1 2 10200 distilled water Lignin 1 1800 14.1 80 2NaOH 128.40 10.3 — 0.0 17.5 3 10200 distilled water Lignin 2 1800 14.280 2 NaOH 111.60 10.2 — 0.0 18.1 4 10200 distilled water Lignin 2 180014.2 80 2 NaOH 111.60 10.2 — 0.0 20.1 6 3854 tap water Lignin 3 109214.8 80 2 NaOH 54.00 9.6 — 0.0 15.9 Ludwigsfelde 7 3854 tap water Lignin3 1092 14.8 80 2 NaOH 54.00 9.6 — 0.0 15.9 Ludwigsfelde 8 3854 tap waterLignin 3 1092 14.8 80 2 NaOH 54.00 9.6 — 0.0 15.9 Ludwigsfelde 9 3854tap water Lignin 3 1092 14.8 80 2 NaOH 54.00 9.6 — 0.0 15.9 Ludwigsfelde10 3854 tap water Lignin 3 1092 14.8 80 2 NaOH 54.00 9.6 — 0.0 15.9Ludwigsfelde 11 48.23 distilled water Lignin 1 20.9 14.1 80 2 NaOH 0.449.8 — 0.0 17.7

The composition of the lignin used is indicated in Table 2.

TABLE 2 Lignin 1 Lignin 2 Lignin 3 C 62.8 64.0 67.2 H 4.8 5.2 5.5 O(calculated) 24.8 24.0 24.0 N 0.3 0.0 0.0 S 1.3 1.5 1.8 Na 2.5 1.9 0.3Ash (without Na) 3.6 4.1 1.2

In the second step, the liquid containing the renewable raw material issubjected to a hydrothermal treatment and thus a solid is obtained.

The solution prepared in the first step is heated from a startingtemperature (10) for a heating time (11) to a reaction temperature (12)that is maintained for a reaction period (13). Subsequently, cooling fora cooling time (14) to an end temperature (15) is effected. As a result,a solid is obtained. In dependence on the aforementioned processconditions the pH value (16) and the conductivity (17) of the liquidcontaining the solid are changed.

With an appropriate adjustment of the content of organic dry matter, thepH value and the concentration of inorganic ions in the first step, andan appropriate choice of the process conditions in the second step,conditions are obtained in the second step at which the particulatecarbon material separates from the solution in a raw form. The processconditions of the second step are indicated in Table 3.

TABLE 3 Example 10 11 12 13 14 15 16 17 — ° C. min ° C. min min ° C. —mS/cm 1 80 90 240 150 3600 80 9.0 19.7 2 80 90 240 150 3600 80 9.1 21.43 80 90 240 150 3600 80 8.6 20.2 4 80 90 240 150 3600 80 8.4 21.1 6 3040 225 324 40 30 8.4 13.2 7 30 40 225 408 40 30 8.3 13.5 8 30 41 230 27041 30 8.3 13.5 9 30 41 230 300 41 30 8.2 13.7 10 30 42 235 162 42 30 8.712.9 11 30 41 230 180 41 30 8.6 20.9

In the third step, the raw particulate carbon material is dewatered andpossibly washed. The raw particulate carbon material is largelyseparated from the liquid containing the same by a dewatering step (18).Subsequently, the raw particulate carbon material is washed with amultiple amount of water and dewatered again. The process conditions ofthe third step are summarized in Table 4.

TABLE 4 19 Amount of washing liquid kg/kg of Example 18 dry particulate— Device Type Washing liquid carbon material 1 centrifuge; 6000resuspension/centrifuge; 6000 distilled water 3 RPM/15 min RPM/15 min 2centrifuge; 6000 resupension/centrifuge; 6000 3 RPM/15 min RPM/15 min 3centrifuge; 6000 resuspension/centrifuge; 6000 3 RPM/15 min RPM/15 min 4centrifuge; 6000 resuspension/centrifuge; 6000 3 RPM/15 min RPM/15 min 6centrifuge; 9000 resuspension/centrifuge; 9000 tap water 2 RPM/15 minRPM/15 min Ludwigsfelde 7 centrifuge; 9000 resuspension/centrifuge; 90002 RPM/15 min RPM/15 min 8 centrifuge; 9000 resuspension/centrifuge; 90002 RPM/15 min RPM /15 min 9 centrifuge; 9000 resuspension/centrifuge;9000 2 RPM/15 min RPM/15 min 10 centrifuge; 9000resuspension/centrifuge; 9000 2 RPM/15 min RPM/15 min 11 centrifuge;9000 resuspension/centrifuge; 9000 2 RPM/15 min RPM/15 min

In the fourth step, the dewatered and possibly washed raw particulatecarbon material is dried and possibly ground.

The dewatered raw particulate carbon material and remaining liquid isdried at an elevated temperature (20, see Table 5), whereby theparticulate carbon material is obtained. Subsequently, the particulatecarbon material can be de-agglomerated (21, see Table 5).

TABLE 5 Example 20 21 — ° C. — 1 105 jet mill with classifier wheel 2105 jet mill with classifier wheel 3 105 jet mill with classifier wheel4 105 jet mill with classifier wheel 6 105 — 7 105 — 8 105 — 9 105 — 10105 — 11 105 —

Quality of the obtained particulate carbon material from Examples 1-11:In the end, an expression of the particulate carbon material accordingto the invention is obtained (see Table 6):

TABLE 6 Car- Oxy- bon gen Ash average D50/ Wt-% Wt-% con- sphere averageWater dry, dry, tent OAN diam- sphere con- Exam- ash- ash- Wt-% STSAValue pH)¹ BB)² D/G)³ D50)⁴ D90)⁴ D99)⁴ eter )⁵ diameter BET tent plefree free dry m²/g ml/100 g — % — μm μm μm μm — m²/g % 72.3 21.7 4.917.7 94.4 8.7 9.8 0.52 1.6 3.1 4.4 0.23 7.0 19.9 0.8 2 71.9 22.3 4.612.6 80.5 8.5 9.5 0.65 1.5 2.8 4.0 0.32 4.7 14.2 1.9 3 70.9 22.8 5.313.6 84.1 8.8 n.d. n.d. 1.4 2.4 3.2 0.29 4.7 14.4 1.3 4 70.7 22.8 5.310.8 74.0 8.8 n.d. n.d. 1.5 2.6 3.3 0.37 4.1 10.0 1.5 6 69.5 n.d. n.d.26.9 n.d. n.d. n.d. n.d. n d. n.d. n.d. 0.15 n.d. 28.3 1.5 7 89.8 n.d.n.d. 19.2 n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0.21 n.d. 20.2 2.4 8 70.1n.d. n.d. 14.0 n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0.29 n.d. 14.7 1.3 970.2 n.d. n.d. 9.9 n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0.40 n.d. 10.4 1.610 70.4 n.d. n.d. 2.6 n.d. n.d. n.d. n.d. n.d. n.d. n.d. 1.56 n.d. 2.7 211 70.3 n.d. n.d. 36.7 n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0.11 n.d. 38.61.3 ¹= in 15% suspension; ²= resistance to bases in % of the dissolvedmaterial; ³= from the Raman spectrum; ⁴= from the grain sizedetermination by means of laser diffraction ⁵= calculated from STSA andparticle density; n.d. = not determined

Examples 12A-D and Reference Example for the Manufacture of RubberArticles Made of SBR with the Particulate Carbon Material from Examples1 and 2 or with Carbon Black N 660

The carbon materials obtained according to the exemplary embodiments 1and 2 are introduced into a rubber mixture as filler and vulcanized bymeans of further additives. The composition of the rubber mixture isshown in Table 7.

TABLE 7 Reference A B C D Elastomer sSBR sSBR sSBR sSBR sSBR — typeElastomer 100 100 100 100 100 phr quantity Filler type N660 particulateparticulate particulate particulate — carbon carbon carbon carbonmaterial acc. material acc. material acc. material acc. to Ex. 2 to Ex.2 to Ex. 1 to Ex. 2 Filler quantity 40 40 40 40 60 phr Coupling — — Si69Si69 Si69 — reagent Type Coupling — — 3.2 3.2 4.8 phr reagent QuantityZnO 3 3 3 3 3 phr Stearic acid 2 2 2 2 2 phr DPG 2 2 2 2 2 phr CBS 1.51.5 1.5 1.5 1.5 phr Sulfur 1.5 1.5 1.5 1.5 1.5 phr phr: parts perhundred rubber, quantity based on elastomer quantity DPG, CBS:vulcanization accelerator Si69: coupling reagent

As SBR, solution SBR (sSBR) Buna VSL 4526-0 HM of Lanxess was used. Itis a copolymer comprising 26 wt-% styrene beside butadiene. Its Mooneyviscosity is 65 ME (ASTM D 1646). Zinc oxide, stearic acid and sulfurwere obtained from Fischer Scientific. 2-N-cyclohexyl benzothiazolesulfenamide (CBS) was obtained from Lanxess. 1,3-Diphenylguanidine (DPG)was used from Sigma-Aldrich Co., LLC, USA. The process oil TDAE (VIVATEC500) was obtained from Klaus Dahleke KG. The antioxidant2,2,4-trimethyl-1,2-dihydroquinoline polymer TMQ was supplied byC.H.Erbslöh, Krefeld. N-(1,3-dimethylbutyl)-1V-phenyl-P-phenylenediamine(6PPD) was obtained from abcr GmbH & Co. K G, Karlsruhe.Bis(triethoxysilylpropyl)tetrasulfide was used as coupling reagent,which is sold by Evonik Industries under the name Si69®.

SBR was placed in the internal mixer (Haake Rheomix 600P, ThermoFisherScientific, Karlsruhe) at 145° C. and a fill factor of 0.7,corresponding to a volume of 56 cm³. Subsequently, the fillers wereadded in two stages. For the complete silanization, after possiblyadding the silane Si69, the temperature in the internal mixer was keptin a range between 140-165° C. for 10 min and mixing was effected at arotational speed of 60 min⁻¹.

The addition of the antioxidants and vulcanization additives waseffected on a two-roller rolling mill (Polymix-110L, Servitec MaschinenService GmbH, Wustermark) at a starting temperature of 50° C. and aconstant friction of 1:1.2.

The rubber mixtures Reference and A (Table 7) are cross-linked by usinga vulcanization process customary for the application of carbon black.The rubber mixtures B, C and D (Table 7) are cross-linked by using avulcanization process customary for the application of silica togetherwith Si69. The samples were vulcanized in a laboratory press TP1000(Fontijne Grotnes B. V., Vlaardingen, Netherlands) at 160° C. and apressing force of 150 kN. The optimum vulcanization time t₉₀ wasdetermined by means of a Rubber Process Analyzer (Scarabaeus SIS-V50,Scarabaeus GmbH, Wetzlar).

The mechanical characterization was made on DIN S2 test specimensaccording to DIN 53504 with a Zwick/Roell-Z010 materials testing machine(Zwick GmbH & Co KG, Ulm) with optical strain sensor at a crossheadspeed of 200 mm/min at room temperature. The stress-strain distributionsin the tensile test as an example for the rubber-technologicalproperties of the obtained rubber articles from Examples A-D of Table 7are indicated in the diagram of FIG. 1.

In particular in the case of Examples B, C and D (in which a couplingreagent is added) the same show comparable properties as the fillerN660. The values for the modulus 50%, modulus 100% and modulus 200% ofExamples B and C are at least as high as for the Reference. Furthermore,it is shown that the increase of the filling degree from 40 phr (B) to60 phr (D) of the particulate carbon material according to Example 2 ata strain in the lower range (up to 100%) leads to an increase of thestress values, i.e, of the modulus 50% and of the modulus 100%. Inaddition, it becomes clear that an increase of the STSA surface area andthe OAN value of the particulate carbon material from the values ofExample 2 to the values of Example 1 at the same filling degree leads toan improvement of the tensile strength and to higher values of themodulus 50%, modulus 100% and modulus 200% (compare B and C).Furthermore, it becomes clear that the particulate carbon material fromExample 2 with its STSA surface area of 12.6 m²/g already shows acomparable stress-strain distribution in the tensile test as theclassical carbon black N660, which is characterized by an STSA surfacearea of 34 m²/g±5 m²/g.

The loss factor tan delta (quotient of loss modulus E° and storagemodulus E′ of the elastomer material) in dependence on the temperature,determined in a dynamic mechanical analysis (temperature sweep), isshown in FIG. 2 and Table 8.

The mixtures with N660 (reference) and those with the particulate carbonmaterial from Example 2 without coupling reagent (Example 12A) showsimilar glass transition temperatures (T_(g,SBR)=−2.91° C.; see the peakof the curve tan delta vs. temperature in FIG. 2). These two mixturesalso have a similar rigidity in the rubber plateau region above theglass transition temperature. The tan delta curves are close to eachother, wherein the curve of the reference mixture from about 76° C.however is slightly lower than that of Example 12A and thus indicates aslightly lower energy loss.

The use of the particulate carbon material from Example 2 in combinationwith a coupling reagent (Example 12B) leads to significant changes. Ascompared to Reference and 12A, the glass transition temperature of themixture of Example 12B is shifted upwards to T_(g,SBR)=−0.48° C. Underthe conditions of a weak dynamic elongation (0.5%) the energy lossproperties of the mixture 12B are distinctly improved with respect tothe Reference with N660, which is revealed by the lower curve profile inthe temperature range above the glass transition temperature.

It can be seen that the elastomer material that contains the particulatecarbon material from Example 2 and a coupling reagent has lower valuesas compared to the Reference with N660 for tan delta above the glasstransition temperature, which allows a comparatively reduced rollingfriction to be expected for a tire made of this material.

TABLE 8 tan delta 60° C. tan delta 0° C. Reference N660 0.1020 1.4342Example 12 A 0.1035 1.4023 Example 12 B 0.0840 1.6208

FIG. 2 also reveals that the tan delta of Example 12B is higher at 0° C.than for the Reference, which allows an improved wet grip of a tire madeof the mixture of Example 12B to be expected.

Comparative Example 13 for the Manufacture of Rubber Articles from SBRwith Untreated Lignin

According to the prior art, untreated lignin has already been used inrubber mixtures. The following comparative example shows the differenteffect of untreated lignin and of the carbon material according to theinvention in a rubber mixture.

Lignin 3 from Table 2 is introduced into a rubber mixture as filler forcomparison and vulcanized by means of further additives. The compositionof the rubber mixture corresponds to the composition in Example 12B,wherein however untreated lignin 3 now is used instead of theparticulate carbon material from Example 2. The rubber mixture forExample 13 is cross-linked by using a vulcanization process customaryfor the application of silica together with Si69.

The stress-strain distribution in a tensile test as an example for therubber-technological properties of the obtained rubber article isindicated in the diagram of FIG. 3 together with the results of Example12A and 12B.

It can be seen that even when the coupling reagent silane Si69 is used,the effect in the rubber mixture caused by untreated lignin (Example 13)is distinctly weaker than the effect caused by the carbon materialaccording to the invention as such (Example 12A) and quite particularlydistinctly lags behind the effect of the carbon material according tothe invention in combination with silane Si69 (Example 12B).

Example 14 for the Determination of the ¹⁴C Content in the Product ofExample 2

For the purpose of determining the ¹⁴C content the material of Example 2was supplied to the Poznan Radiocarbon Laboratory, Foundation of the A.Mickiewicz University, ul. Rubież 46, 61-612 Poznan. The used method isdescribed by the head of the laboratory, Tomasz Goslar, on the Internetsite of the institute. The contents essential for lignin are summarizedbelow.

Procedure for ¹⁴C dating by means of AMS technology with the followingsteps:

chemical pretreatmentproduction of CO₂ and graphitization¹⁴C measurement by AMScalculation and calibration of the ¹⁴C age

The methods of the chemical pretreatment are described in principle inBrock et al., 2010, Radiocarbon, 52, 102-112.

Samples of plant residues are treated with 1 M HCl (80′C, 20+ min),0.025-0.2 M NaOH (80′C) and then with 0.25 M HCl (80° C., 1 h). Aftertreatment with each reagent, the sample is washed with deionized water(Millipore) to pH=7. For the first HCl treatment a longer period (20+)is used, when the sample still reveals the development of gas bubbles.The step of the NaOH treatment is repeated several times, in generaluntil no more coloration of the NaOH solution occurs (the coloration ofthe solution is caused by humic acids dissolved in NaOH), but the NaOHtreatment is stopped when there is a risk of the complete dissolution ofthe sample.

In the case of organic samples the CO₂ is produced by combustion of thesample.

The combustion of the sample is carried out in the closed quartz tube(under vacuum) together with Cu© and Ag wool at 900° C. for 10 hours.The obtained gas (CO₂+steam) then is dried in a vacuum apparatus andreduced with hydrogen (H₂) by using 2 mg of Fe powder as catalyst. Theobtained mixture of carbon and iron then is pressed into a specialaluminum holder corresponding to the description of Czernik J., GoslarT., 2001, Radiocarbon, 43, 283-291. In the same way, the standardsamples are produced, e.g. samples that contain no ¹⁴C (coal or IAEA C1Carrara marble) and samples of the “International modern ¹⁴C standard”(oxalic acid II).

The measurements described here are carried out in the AMS ¹⁴Claboratory of A. Mickiewicz University in Poznań.

The content of ¹⁴C in the carbon sample is measured with thespectrometer “Compact Carbon AMS” (manufacturer: National ElectrostaticsCorporation, USA), which is described in the article Goslar T., CzernikJ., Goslar E., 2004, Nuclear Instruments and Methods B, 223-224, 5-11.The measurement is based on the comparison of the intensities of the ionbeams of ¹⁴C, ¹³C and ¹²C, which are measured for each sample and eachstandard (modern standard: “oxalic acid II” and standard for carbon freefrom ¹⁴C (“background”). In each AMS run 30-33 samples of unknown ageare measured in alternation with 3-4 measurements of the modern standardand 1-2 background measurements. When organic samples are dated, thebackground is represented by coal.

Conventional ¹⁴C age is calculated by using the correction for theisotope fractionation (according to Stuiver, Polach 1977, Radiocarbon19, 355), based on the ratio ¹³C/¹²C which is determined in the AMSspectrometer simultaneously with the ratio ¹⁴C/¹²C (note: the measuredvalues of δ¹³C depend on the isotope fractionation during the CO₂reduction and the isotope fractionation within the AMS spectrometer, andas such they cannot be compared with the values δ¹³C that are determinedfor gas samples with conventional mass spectrometers). The uncertaintyof the calculated ¹⁴C age is determined by means of the uncertaintyresulting from the count statistics, likewise the scattering (standarddeviation) of the individual ¹⁴C/¹²C results. The uncertainties of the¹⁴C/¹²C ratios measured for the standard samples are additionally takeninto account. The 1-sigma uncertainty of the conventional ¹⁴C age, whichis indicated in the report, is the best approximation of the absoluteuncertainty of the measurement.

The calibration of the ¹⁴C age is carried out with the program OxCalver. 4.2 (2014) the fundamentals of which are described in Bronk RamseyC., 2001, Radiocarbon, 43, 355-363, while the current version isdescribed in Bronk Ramsey C., 2009, Radiocarbon, 51, 337-360 and BronkRamsey C. and Lee S., 2013, Radiocarbon, 55, 720-730. The calibration ismade against the latest version of the ¹⁴C calibration curve, i.e.INTCAL13 (Reimer P. J., et al. 2013, Radiocarbon, 55(4), 1869-1887).

The analysis provides the age of the carbon sample for archaeologicalpurposes. The measurement result however can also be indicated as thespecific activity. In the present case of the material of Example 2, theanalysis provided a value of 243.30±0.52 Bq/kgC or Bq/kg of carbon forthe specific activity.

Example 15 for the Manufacture of Rubber Articles from SBR with theParticulate Carbon Material of Example 2 in the Presence of a ReagentMasking Functional Groups

The carbon material obtained according to exemplary embodiment 2 isintroduced into a rubber mixture as filler and vulcanized by means offurther additives. The composition of the rubber mixture and itsprocessing corresponds to that of Example 12B (Table 7), wherein howeverthe silane Si69 is replaced in equimolar proportion bytriethoxymethylsilane, which corresponds to a use of 1.06 phr. Thefurther processing also is analogous to Example 12.

The triethoxymethylsilane is not able to be incorporated into thecross-linkage via sulfur bridges. However, it reacts with the surface ofthe carbon material according to the invention by consuming thefunctional groups. The functional groups reacting with the silane areoutwardly replaced by methyl groups, which as compared to thenon-modified starting material leads to a compatibilization of thefiller surface with the non-polar rubber matrix.

The carbon material according to the invention treated withtriethoxymethylsilane for example effects a higher tensile strength inthe rubber as compared to the carbon material used without silane, butas expected lags behind the carbon material in combination with thecoupling silane Si69.

The stress-strain distribution in a tensile test as an example for therubber-technological properties of the obtained rubber articles of FIG.4 shows that in selected rubber systems and for selected applications itmay be expedient to perform a masking of the functional groups.

Examples 16 A and B as Well as Reference for the Manufacture of RubberArticles from NR/BR with the Particulate Carbon Material of Example 2 orwith Carbon Black N660

The carbon material obtained according to exemplary embodiment 2 isintroduced as filler into a mixture of NR and BR and vulcanized by meansof further additives.

In the case of A and the Reference a mixture (pre-mix) of NR and BRinitially is prepared in the internal mixer (Haake Rheomix 600P,ThermoFisher Scientific, Karlsruhe) at a starting temperature of 120°C., which then is mixed with the respective filler and furthercomponents. In the case of B by contrast a master batch of BR, thefiller and silane initially is prepared in the internal mixer (startingtemperature 35° C., rotational speed 60 min⁻¹), which subsequently isfurther processed with NR and the remaining components (likewise in theinternal mixer, starting temperature 120° C., rotational speed 60min⁻¹). The quantity composition of both processing variants isidentical.

The stress-strain distributions in the tensile test as an example forthe rubber-technological properties of the obtained rubber articles fromExamples A and B are indicated in the diagram of FIG. 5. The same showthat in NR/BR mixtures the carbon material according to the inventioncan be used for reinforcement. Furthermore, it can be seen that theorder of processing has an influence on the performance of the filler inthe articles made of the respective NR/BR rubber mixture in thecross-linked condition. In this way, modulus and tensile strength can beinfluenced.

Examples 17 A and B as Well as Reference for the Manufacture of RubberArticles from NBR by Using the Particulate Carbon Material of Example 4or N 990

The carbon material obtained according to exemplary embodiment 4 isintroduced into NBR as filler and vulcanized by means of furtheradditives, but without a coupling reagent. The composition of the rubbermixture is shown in Table 9.

TABLE 9 Reference A B Perburan 3945 100.0 100.0 100.0 ZnO 5.0 5.0 5.0Stearic acid 1.0 1.0 1.0 Mesamoll II 15.0 15.0 15.0 Talc 80.0 80.0 80.0N 500 30.0 30.0 30.0 N 990 80.0 40.0 Material of Example 4 40.0 80.0Vulkanox 4010 3.0 3.0 3.0 Sulfur 0.5 0.5 0.5 MBTS 1.0 1.0 1.0 TMTD 3.03.0 3.0

The mixtures are prepared on a Haake Rheomix 600 (tangential rotorgeometry, 78 cm³) with a starting temperature of 40° C. and a rotorspeed of 100 min⁻¹. Initially, the NBR polymer is mixed for 2 min, thenin addition stearic acid, ZnO, possibly material from Example 4 andtalcum for 2 min, in addition possibly N990 and Mesamoll II for another4 min, antioxidants for another 3 min, and the vulcanization chemicalsfor another 2 min. The optimum vulcanization time was determined bymeans of a Rubber Process Analyzer and the mixture was vulcanized at160° C. for a minute value of (t₉₀+1/mm of layer thickness).

The determination of the Shore A hardness was effected according to DIN53505; 2000-08, the tensile test according to DIN 53504:2009-10, and thestorage for 72 h at 70° C. in oil Lubrizol OS 206304 according to DINISO 1817:2008-08.

The values shown in Table 10 were obtained.

TABLE 10 Example Reference A B Shore A hardness 83 84 85 Tensilestrength (MPa) 9.9 11.1 11.4 Elongation at break (%) 235 253 248 Modulus(MPa) 50% 4.7 5.3 5.6 100% 6.6 7.5 8.0 200% 9.7 10.8 11

It becomes clear that both with a partial and with a completereplacement of N 990 by the carbon material according to the inventionof Example 4 without the addition of a coupling reagent, comparable oreven slightly improved values are achieved in the tensile test, see FIG.6. The same applies for the variations of the values after storage inoil as shown in Table 11. When replacing inactive carbon blacks such asN 990, the use of the carbon material according to the invention in itsquality according to Example 4 without a coupling reagent is sufficientto achieve comparable values.

TABLE 11 Changes after storage in engine oil 72 h/70° C. Reference A Bin the weight % −2.6 −2.6 −2.7 in the volume % −3.4 −3.3 −3.3 in thehardness +3 +3 +3 in the tensile strength % +6 +12 +11 in the elongationat break % −9 −6 −10

We claim:
 1. A multi-stage method for the hydrothermal treatment ofrenewable raw materials, comprising: providing a liquid containing therenewable raw material; subjecting the liquid containing the renewableraw material to a hydrothermal treatment at a temperature between 150°C. and 250° C.; substantially separating solid present after thehydrothermal treatment from the liquid; and removing residual moistureof the solid by drying, whereby a particulate carbon material isobtained; wherein the statistical thickness surface area (STSA) and theoil absorption number (OAN) of the particulate carbon material obtainedwhile removing the residual moisture by mutually matching: theconcentration of the organic dry matter of the renewable raw material inthe liquid containing the renewable raw material, the pH value of theliquid containing the renewable raw material, the concentration ofinorganic ions in the liquid containing the renewable raw material, thetemperature of the hydrothermal treatment, and the residence time in thehydrothermal treatment, such that an STSA in a range between 5 m²/g and200 m²/g and an OAN in a range between 50 ml/100 g and 150 ml/100 g areobtained.
 2. The method according to claim 1, wherein a concentration ofinorganic ions in the liquid containing the renewable raw material isdetermined by measuring the conductivity of the liquid containing therenewable raw material.
 3. The method according to one of the precedingclaims, wherein a particulate material is produced by the mutualcoordination of conditions in the hydrothermal treatment.
 4. The methodaccording to one of the preceding claims, wherein: temperature andresidence time are adjusted while subjecting the liquid containing therenewable raw material to the hydrothermal treatment, so as to achievethe STSA in the range between 5 m²/g and 200 m²/g and the OAN in therange between 50 ml/100 g and 150 ml/100 g; and the method furtherincludes: obtaining a slightly higher concentration of inorganic ionsthan is initially obtained after the adjustment of the organic drymatter content of the renewable raw material in the liquid containingthe same and the adjustment of the pH value, and subsequently effectinga further increase of the concentration of inorganic ions by addition ofsalts, until the concentration of inorganic ions, as measured by theconductance, appropriate for the process conditions of the hydrothermaltreatment is achieved.
 5. The method according to one of the precedingclaims, wherein the adjustment of the concentration of the organic drymatter of the renewable raw material in the liquid containing therenewable raw material, of the pH value of the liquid containing therenewable raw material, and/or of the concentration of inorganic ions inthe liquid containing the renewable raw material is effected whileproviding a liquid containing the renewable raw material.
 6. The methodaccording to one of the preceding claims, wherein the adjustment of theconcentration of the organic dry matter of the renewable raw material inthe liquid containing the renewable raw material, of the pH value of theliquid containing the renewable raw material, and/or of theconcentration of inorganic ions in the liquid containing the renewableraw material is effected while providing a liquid containing therenewable raw material and while subjecting the liquid containing therenewable raw material to the hydrothermal treatment.
 7. The methodaccording to one of the preceding claims, wherein the adjustment of theconcentration of the organic dry matter of the renewable raw material inthe liquid containing the renewable raw material, of the pH value of theliquid containing the renewable raw material, and/or of theconcentration of inorganic ions in the liquid containing the renewableraw material is effected while subjecting the liquid containing therenewable raw material to the hydrothermal treatment.
 8. The methodaccording to one of claim 6 or 7, wherein: the renewable raw material inthe liquid containing the renewable raw material is completely dissolvedproviding a liquid containing the renewable raw material; and desiredfinely divided particles are formed during the hydrothermal treatmentsubjecting the liquid containing the renewable raw material to ahydrothermal treatment, by not only chosen process conditions of thehydrothermal treatment, but in addition by: an increase of aconcentration of organic dry matter of the renewable raw material in theliquid containing the renewable raw material, a decrease of a pH valueof the liquid containing the renewable raw material, or an increase of aconcentration of inorganic ions in the liquid containing the renewableraw material.
 9. The method according to claim 8, further comprising,after completion of formation of desired finely divided particles:decreasing the concentration of the organic dry matter in the liquidcontaining the particulate carbon material, increasing the pH value ofthe liquid containing the particulate carbon material, or decreasing theconcentration of the inorganic ions in the liquid containing theparticulate carbon material.
 10. The method according to one of thepreceding steps, wherein the STSA and the OAN of the particulate carbonmaterial are controlled by adjusting: the concentration of the organicdry matter of the renewable raw material in the liquid containing therenewable raw material to a value between 5 wt-O % and 40 wt-%, the pHvalue of the liquid containing the renewable raw material at 20° C. to25° C. to a value ≥7, more preferably ≥8, the concentration of inorganicions in the liquid containing the renewable raw material p to a valuebetween 10 mS/cm and 200 mS/cm, the temperature of the hydrothermaltreatment to a maximum value between 200° C. and 250° C. and/or theresidence time in the hydrothermal treatment preferably to a periodbetween 1 minute and 6 hours.
 11. The method according to any of thepreceding claim, wherein: the renewable raw material is lignin; aconcentration of organic dry matter of the provided liquid containinglignin in in a range between 10 wt-% and 20 wt-%, a pH value of theprovided liquid containing lignin in a range between 8.5 and 10.5, aconcentration of inorganic ions of the provided liquid containing ligninis such that conductivity of the provided liquid is in a range between10 mS/cm and 25 mS/cm, a maximum temperature of the hydrothermaltreatment is in a range between 210° C. and 240° C., and residence timeof the liquid containing lignin in the hydrothermal treatment is in arange between 120 and 240 minutes, whereby: particulate carbon materialthus produced, measured after the solid is substantially separated fromthe liquid and the residual moisture is dried, has an STSA in a rangebetween 5 m²/g and 50 m²/g and an OAN in a range between 50 ml/100 g and100 ml/100 g.
 12. The method according to one of the preceding claims,wherein the renewable raw material is completely dissolved in theprovided liquid containing the renewable raw material.
 13. The methodaccording to one of the claims 1-11, wherein: the renewable raw materialis not completely dissolved in the provided liquid containing therenewable raw material; and the method further comprises adjusting atleast one of the following parameters, such that, due to a temperatureincrease during the hydrothermal treatment, the renewable raw materialinitially is dissolved completely prior to the sold being generated inthe hydrothermal treatment: a concentration of organic dry matter of therenewable raw material in the liquid containing the renewable rawmaterial, a pH value of the liquid containing the renewable rawmaterial, and a concentration of inorganic ions in the liquid containingthe renewable raw material.
 14. The method according to one of thepreceding claims, wherein: the method is operated continuously, processconditions of the hydrothermal treatment are kept constant, and acontinuous adjustment of a pH value and conductance of the liquidcontaining the renewable raw material as the liquid is provided.